Question

Electric field lines of magnitude 5.7 × 104 N/C pass through a circular loop of radius 15 cm. Calculate the electric flux when the face of the loop is perpendicular to the electric field lines.

Answer 1

$$\begin{gathered} \mathrm{Electric}\mathrm{flux}: \\ \mathrm{\varphi }=\mathrm{EA} \\ \mathrm{where} \\ \mathrm{E}=\mathrm{Electric}\mathrm{field} \\ \mathrm{A}=\mathrm{Cross}-\mathrm{sectional}\mathrm{area}\mathrm{of}\mathrm{the}\mathrm{loop} \\ ={\mathrm{\pi r}}^2 \\ \mathrm{Hence}, \\ \mathrm{\varphi }=\mathrm{E}\left({\mathrm{\pi r}}^2\right) \\ =\left(5.7\times {10}^4\right)\left(\mathrm{\pi }\right){\left(0.15\right)}^2 \\ \mathbf{}\mathbf{}\mathbf{}\mathbf{=}\mathbf{4029}\mathbf{.}\mathbf{1}\mathbf{}\mathbf{N}\mathbf{.}{\mathbf{m}}^{\mathbf{2}}\mathbf{/}\mathbf{C} \end{gathered}$$